In a manner that shows disapproval; with an expression or tone showing that something is wrong or unacceptable.
From 'disapproving' (present participle of 'disapprove') + '-ly' (adverb suffix). This creates an adverb describing how an action is performed with disapproval.
This is one of the few words in this list that's actually used in modern writing! 'She looked at him disapprovingly' is natural English—the '-ly' adverb formation works especially well with emotional or evaluative verbs.
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